Allow specifying custom timestamps for events

Adding event with timestamp is not yet a part of the OpenTelemetry
specification, but this function will come in handy when implementing
the OpenTracing bridge.

api/trace/api.go

@@ -71,6 +71,9 @@ type Span interface {
 
 	// AddEvent adds an event to the span.
 	AddEvent(ctx context.Context, msg string, attrs ...core.KeyValue)
+	// AddEventWithTimestamp adds an event with a custom timestamp
+	// to the span.
+	AddEventWithTimestamp(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue)
 
 	// IsRecordingEvents returns true if the span is active and recording events is enabled.
 	IsRecordingEvents() bool

api/trace/current_test.go

@@ -3,6 +3,7 @@ package trace_test
 import (
 	"context"
 	"testing"
+	"time"
 
 	"google.golang.org/grpc/codes"
 
@@ -108,6 +109,10 @@ func (mockSpan) Tracer() trace.Tracer {
 func (mockSpan) AddEvent(ctx context.Context, msg string, attrs ...core.KeyValue) {
 }
 
+// AddEventWithTimestamp does nothing.
+func (mockSpan) AddEventWithTimestamp(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue) {
+}
+
 // AddLink does nothing.
 func (mockSpan) AddLink(link trace.Link) {
 }

api/trace/noop_span.go

@@ -16,6 +16,7 @@ package trace
 
 import (
 	"context"
+	"time"
 
 	"google.golang.org/grpc/codes"
 
@@ -75,6 +76,10 @@ func (NoopSpan) Tracer() Tracer {
 func (NoopSpan) AddEvent(ctx context.Context, msg string, attrs ...core.KeyValue) {
 }
 
+// AddEventWithTimestamp does nothing.
+func (NoopSpan) AddEventWithTimestamp(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue) {
+}
+
 // SetName does nothing.
 func (NoopSpan) SetName(name string) {
 }

experimental/streaming/sdk/span.go

@@ -112,6 +112,10 @@ func (sp *span) AddEvent(ctx context.Context, msg string, attrs ...core.KeyValue
 	sp.addEventWithTime(ctx, time.Time{}, msg, attrs...)
 }
 
+func (sp *span) AddEventWithTimestamp(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue) {
+	sp.addEventWithTime(ctx, timestamp, msg, attrs...)
+}
+
 func (sp *span) addEventWithTime(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue) {
 	observer.Record(observer.Event{
 		Time:       timestamp,

sdk/trace/span.go

@@ -158,6 +158,13 @@ func (s *span) AddEvent(ctx context.Context, msg string, attrs ...core.KeyValue)
 	s.addEventWithTimestamp(time.Now(), msg, attrs...)
 }
 
+func (s *span) AddEventWithTimestamp(ctx context.Context, timestamp time.Time, msg string, attrs ...core.KeyValue) {
+	if !s.IsRecordingEvents() {
+		return
+	}
+	s.addEventWithTimestamp(timestamp, msg, attrs...)
+}
+
 func (s *span) addEventWithTimestamp(timestamp time.Time, msg string, attrs ...core.KeyValue) {
 	s.mu.Lock()
 	defer s.mu.Unlock()